Jorn has designed such an easy API for GUPnP that I've
already implemented the UPnP part of the network light. Now
I'll turn towards the GUI which is quite simple now that
I've these images:

The first one I borrowed from the Tango project and it's
obviously made by some professional but the second one is a
modification on my own using Gimp. I'll still be thankful to
anyone who can make me a nicer version of the second image.
Note that I've removed the shadow from the second one and I
did that because the shadow becomes quite dark when i
alpha-composite the two images with alpha set to max.